From: Jonathan Morton <chromatix99@gmail.com>
To: Dave Taht <dave.taht@gmail.com>
Cc: Adrian Popescu <adriannnpopescu@gmail.com>,
Cake List <cake@lists.bufferbloat.net>
Subject: Re: [Cake] CAKE set-associative hashing
Date: Mon, 30 Oct 2017 00:39:47 +0200 [thread overview]
Message-ID: <CAJq5cE2i9E9gW-aAy5ts5Bkp+UB8Rhu22nEnE2fnLUm8t69whg@mail.gmail.com> (raw)
In-Reply-To: <CAA93jw5dQUebb-WvW9Xrvhkh4W1CUmNJOKSsFxXX3uY-Pyz4bw@mail.gmail.com>
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In CPUs, 4-way is now common in first-level caches, 16-way at last-level.
It is a tradeoff between guaranteed hit latency (necessary in synchronous
hardware) and collision rate. In software, average hit latency is usually
more relevant, and worst-case throughput otherwise.
IMHO, having a separate qdisc tree per hardware queue is the wrong design.
Better would be a single qdisc (or tree thereof) that can be drained
concurrently into all queues. That currently seems to be easiest to
arrange by putting the qdiscs in userspace, but theoretically that need not
be so.
- Jonathan Morton
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prev parent reply other threads:[~2017-10-29 22:39 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-29 10:07 Adrian Popescu
2017-10-29 10:14 ` Jonathan Morton
2017-10-29 15:38 ` Adrian Popescu
2017-10-29 22:20 ` Dave Taht
2017-10-29 22:39 ` Jonathan Morton [this message]
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